The formation of glass into useful and artistic objects dates to at least the 4th Century BCE. Among the established techniques for forming glass are flow-molding, press-molding and hand-blowing. Hand-blown glass objects are admired for the artistry and skill required to produce them, and the uniqueness of each piece so produced. In hand-blowing glass, a skilled artisan gathers a gob of molten glass about the distal end of a gathering implement. The gathering implement is typically hollow so that, as the artisan manipulates the implement to shape the gob, he can blow air into the gob to create a cavity within the work piece. In this general manner, a glassblower is able to create vessels such as cups, bowls and bottles.
As glass is hand-blown, the artisan might add unique features to the work piece. For example, color might be added by incorporating certain metals or minerals into the glass as it is reheated and worked. The inclusion of such features signifies artistry, skill and uniqueness. However, the very nature of the hand-blowing process renders hand-blown pieces expensive and impractical for use as containers for all but the highest-end products such as fine perfumes and select alcoholic beverages.
Contrasting with the artistry associated with hand-blown glass objects is the rapid mass production of strictly utilitarian objects such as window panes and beverage bottles. Among the goals of manufacturing vessels such as drinking glasses and beverage bottles are rapid reproducibility and uniformity of appearance among units. Of particular importance is uniformity among units in physical dimensions such as opening shape and size in order to facilitate the use of standardized lids, plugs or caps as closures. Accordingly, in the modern era, glass vessels are largely produced by strictly-controlled automated hot pressing and blowing processes. Such processes have the advantage of being relatively inexpensive and invariant, but result in products lacking uniqueness and artistry.
A process for producing a multi-tone glass vessel from at least two disparately-colored molten-glass gobs yields vessels combining the artistry and uniqueness traditionally resulting from hand-blowing with the dimensional reproducibility required for mass production.